Mariana Fruit Dove (Ptilinopus roseicapilla)

Order: ColumbiformesFamily: Columbidae

Description: The Mariana Fruit Dove is a sexually monomorphic forest dove. They have a pearly gray head, neck, breast, and upper back and the rest of their upper parts bright green. The cap and sometimes shorter malar streak, are rose red. Underparts are variegated with purple transverse bar below breast, orange flanks, yellow belly and pinkish orange undertail coverts. The tail band is pale gray. Juvenile plumage (rarely seen) is entirely green (Pratt, 1987). Adult females resemble males but are slightly smaller with a greener neck. On females, the purple transverse bar below the breast tends to be less prominent than in males and the yellow belly of females tends to be less bright than in males (Herb Roberts, unpubl. data)

Distribution: The Mariana Fruit Dove is endemic to the Mariana Islands and is considered common on Saipan, Tinian, Rota, and Aguiguan. The species was extirpated on Guam in the 1980s due to predation by the introduced brown treesnake (Boiga irregularis; Wiles et al. 2005). In 1982, the total population of Mariana Fruit Doves on Saipan, Tinian, Aguiguan, and Rota was reported to be approximately 2,541, 3,075, 292, 3,535 individuals respectively, in 1982 (Enbring et al. 1986). Surveys on Saipan, Tinian, and Aguiguan have been completed since 1982, however, the results of these surveys have not been analyzed. On Rota, subsequent analysis of all island-wide surveys (1982 – current), Rota Bridled white-eye VCP surveys (2002-2005) and BBS surveys (2000-2005) all show a significant decline in Mariana fruit dove populations on Rota (Ha 2006).

Habitat: Lives and nests mainly in native forest, although also occupies secondary forest (Craig 1996). However, Baker (1951) found fruit doves most common in secondary growth and scrub forest habitats, but were also fairly common in undisturbed forest. On Guam, Drahos (1977) found fruit doves in ravine and coastal forest with nine records in mangrove swamp. Fruit doves are rarely found in coastal strand dominated by coconut forest or in savanna (Jenkins 1983). On Saipan, Craig (1996) found fruit doves more often in native forest than disturbed habitats. Fruit Doves seem to concentrate activities in upper to mid level canopy (Craig 1996).

Food and Feeding Habits: The Mariana Fruit Dove is primarily a canopy frugivore but feeds on the fruit, leaves, flowers, and seeds of a wide variety of species (Table 2). Fruit doves have been observed to exhibit agonistic behavior towards conspecifics coming in to feed on fruits (Villagomez 1987). Marshall (1949) observed the following about feeding behavior “fruit doves feed in the upper parts of trees and procur their food by walking along horizontal twigs and reaching up and to the side to pick fruit. Birds generally alight perching crosswise on a twig, then turn and move off along it. They can turn entirely around and move in the opposite direction. When a group starts to feed they appear to become less wary. They will leave the backside of a tree as an observer approaches. They fly at great speed and very straight and always at tree top level.”

Behavior: Fruit doves are often seen flying over the forest canopy for <100m suggesting that they do not defend a territory (Craig 1996). Fruit doves are secretive, usually solitary and difficult to see due to the bright green plumage (Jenkins 1983). Baker (1951) also reported solitary birds sitting quietly in thick vegetation. Frequently fruit doves call back and forth to each other, the initial song evokes a chorus of vocalizations by many other individuals. Fruit doves fly only occasionally but always in a swift and direct manner, usually covering short distances of 20-30 meters at treetop level (Jenkins 1983). Marshall (1949) observed the following behavior “They have 2 tricks to avoid being seen once they have flown into a tree. Either they freeze for up to 15 minutes upon alighting or they alight and repair to further concealment into the tree and then freeze.”

Eggs, incubation, hatching, growth and development: Usually lays 1 egg but clutches with 2 eggs have been recorded. Sub-elliptical eggs are sub-white to creamy with rose tint. Egg measurements are 21.5 x 29 (n=2) (Claridge 1987). Both male and female incubates egg. Young are fed on a milky substance in the lining of the parent’s crop called “pigeon’s milk”. Incubation in captivity is 17-18 days, fledging takes 14-18 days (Herb Roberts, unpubl. data)